1. Field of the Invention
This invention relates to a shift actuator giving fluid pressure to a piston slidably installed in a cylinder, whereby driving a shift operating member for gear shift by the piston.
2. Description of the Related Art
In the conventional art, there are transmissions having a synchronous mechanism for moving a synchro sleeve by a shift fork. And in these transmissions, as shown in Japanese Pat. No. 5280311 (patent literature 1), some have a shift actuator for driving a shift fork. The shift actuator includes a piston slidably installed in a cylinder, a fluid pressure chamber defined opposite to the piston in the cylinder to be supplied with fluid pressure such as oil pressure, and a shift fork (a shift operating member) driven by the piston, whereby the shift fork is driven to the shift direction (the axial direction of a fork shaft) by the piston which slides in the cylinder due to the fluid pressure supplied to the fluid pressure chamber.
Hereupon, in a shift actuator described in the patent literature 1, the shift actuator for driving a shift fork and a hydraulic control device for controlling oil pressure supplied to the shift actuator are integrally provided. And an orifice portion (small-diameter portion) for controlling flow rate of hydraulic oil fed into the shift actuator is installed on an oil passage in the hydraulic control device.
Whereas, the hydraulic control device and the shift actuator may be disposed on mutually separated positions according to the arrangement configuration of a rotation shaft such as an input shaft and an output shaft, and gears in a transmission. This configuration is provided with a hydraulic pipe (oil passage) which is connected from the hydraulic control device to the shift actuator is provided, oil pressure for controlling is supplied from the hydraulic control device to the shift actuator through the hydraulic pipe.
In this case, however, as well as the conventional configuration, when the orifice portion (small-diameter portion) for controlling flow rate of hydraulic oil fed into the shift actuator is provided on the oil passage in the hydraulic control device, it takes a long time until the hydraulic oil is filled into the hydraulic pipe connecting the shift actuator with the hydraulic control device and the fluid pressure chamber, which may prevent securing the satisfactory responsiveness and controllability of the shift actuator.